Medical procedures may involve manipulation of a tool positioned remotely from the operator. For example, the tool may be advanced through a working channel of a surgical instrument (e.g., catheters, endoscopes, etc.) through which the tool is inserted into the body of a patient. In one example, the surgical instrument may be used in the context of minimally invasive surgery, during which medical tools may be inserted into a patient's body through an incision or orifice to access and/or treat tissue. In another example, the surgical instrument may be used in procedures such as biopsies and endoscopy. The surgical instrument may comprise an interior lumen (e.g., a working channel) providing a pathway to the tissue site. Catheters and various tools, such as, for example, a grasping forcep, a biopsy forcep, a cytology brush, a balloon dilator, a snare, a needle, and/or a basket, can be inserted through the working channel of the surgical instrument to access the tissue site.